/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.tsfile.read.common.block.column;

import org.apache.iotdb.tsfile.file.metadata.enums.TSDataType;
import org.openjdk.jol.info.ClassLayout;

import static java.util.Objects.requireNonNull;
import static org.apache.iotdb.tsfile.read.common.block.column.ColumnUtil.checkValidRegion;

/**
 * This column is used to represent columns that only contain null values. But its positionCount has
 * to be consistent with corresponding valueColumn.
 */
public class NullColumn implements Column {

    private static final int INSTANCE_SIZE =
            ClassLayout.parseClass(BooleanColumn.class).instanceSize();

    private final int positionCount;

    private final long retainedSizeInBytes;

    public NullColumn(int positionCount) {
        if (positionCount < 0) {
            throw new IllegalArgumentException("positionCount is negative");
        }
        this.positionCount = positionCount;
        retainedSizeInBytes = INSTANCE_SIZE;
    }

    @Override
    public TSDataType getDataType() {
        throw new UnsupportedOperationException(getClass().getName());
    }

    @Override
    public ColumnEncoding getEncoding() {
        throw new UnsupportedOperationException(getClass().getName());
    }

    @Override
    public boolean mayHaveNull() {
        return true;
    }

    @Override
    public boolean isNull(int position) {
        return true;
    }

    @Override
    public boolean[] isNull() {
        throw new UnsupportedOperationException(getClass().getName());
    }

    @Override
    public int getPositionCount() {
        return positionCount;
    }

    @Override
    public long getRetainedSizeInBytes() {
        return retainedSizeInBytes;
    }

    @Override
    public Column getRegion(int positionOffset, int length) {
        checkValidRegion(getPositionCount(), positionOffset, length);
        return new NullColumn(length);
    }

    @Override
    public Column subColumn(int fromIndex) {
        if (fromIndex > positionCount) {
            throw new IllegalArgumentException("fromIndex is not valid");
        }
        return new NullColumn(positionCount - fromIndex);
    }

    @Override
    public void reverse() {
    }

    public static Column create(TSDataType dataType, int positionCount) {
        requireNonNull(dataType, "dataType is null");
        switch (dataType) {
            case BOOLEAN:
                return new RunLengthEncodedColumn(BooleanColumnBuilder.NULL_VALUE_BLOCK, positionCount);
            case INT32:
                return new RunLengthEncodedColumn(IntColumnBuilder.NULL_VALUE_BLOCK, positionCount);
            case INT64:
                return new RunLengthEncodedColumn(LongColumnBuilder.NULL_VALUE_BLOCK, positionCount);
            case FLOAT:
                return new RunLengthEncodedColumn(FloatColumnBuilder.NULL_VALUE_BLOCK, positionCount);
            case DOUBLE:
                return new RunLengthEncodedColumn(DoubleColumnBuilder.NULL_VALUE_BLOCK, positionCount);
            case TEXT:
                return new RunLengthEncodedColumn(BinaryColumnBuilder.NULL_VALUE_BLOCK, positionCount);
            default:
                throw new IllegalArgumentException("Unknown data type: " + dataType);
        }
    }
}
